Views: 43 Author: Site Editor Publish Time: 2022-10-19 Origin: Site
Brewing reliable and delicious beer requires high-quality raw materials, recipes, and operations. Although hops have achieved great success in the field of modern craft beer, understanding the fermentation process driven by the natural life cycle of yeast is the core of the beer brewing process. In a craft brewery, the brewer will use many tools to manipulate and produce wort, but after the wort is sent to the fermentation tank, the yeast will completely take over all the heavy work of brewing beer. The mature yeast management plan provides the brewery with stable and healthy yeast. The yeast will not be contaminated by pollutants, allowing the brewery to brew delicious beer without hindrance. In this article, we will explain the five major challenges in yeast management and discuss how to overcome these challenges.
Five Challenges of Yeast Management
Maintaining detailed and accurate yeast movement in the fermentation tank is the technique of yeast management. You need to record detailed information about each stage of yeast, which is a very important link. Key factors to record for each re-pitching are:
Original pitch date or received date
Brand/batch harvested from
Brand/batch pitching into
Tank harvested from
Tank pitched into
This information and proper fermentation records will help you solve problematic beer fermentations. Of course, you can also use these data to predict seasonal yeast demand and ensure that the appropriate amount of yeast is accurately placed.
（2）Poor Yeast Reproduction Performance
The fermentation process is the same as other processes in craft beer brewing, and the propagation steps of yeast must be sanitized. During fermentation, necessary disinfection steps are taken to ensure that each successive increase in the culture volume will not be contaminated. When the wort is transferred to the fermentation tank, it must be carried out in a clean and hygienic condition, and all pipes and tanks must be sterilized.
When the yeast is in the breeding stage, a good rule of thumb is to let the yeast increase slowly and the number of yeasts should not exceed 10 times the original. This rule allows healthy yeast cells to reach about 8 times their original volume within 24 hours.
（3）Poor Management Of Many Yeast Strains
The most difficult distribution of many yeast strains is to correctly arrange the corresponding brand of each strain. To cut yeast costs by maximizing re-throwing, the brewer must carefully plan the brewing schedule. Brewers need to use records to allow enough time between brews to cut yeast storage and ensure that each batch of beer has healthy yeast.
The best yeast should be put in within a few days after the parent beer reaches its final gravity, which can ensure the high viability and vitality of the yeast. Of course, often this is impossible. If the yeast must be stored outside the fermentation tank, the necessary conditions must be followed to maximize the service life of the yeast slurry.
Store the yeast in a sealed sterile container;
Hygienic transfer of the yeast slurry from the cone of the fermentation tank to the storage container;
It must be ensured that there is no air in the storage container and the yeast is stored in CO2;
Yeast needs to be stored in a cool place, the temperature is preferably <42°F. A refrigerator is a good place for yeast;
Cross-Contamination Of Yeast Strains
Brewers should take care not to cross-contaminate yeast strains. In the beer production line, after brewing a batch of beer, it is necessary to use the CIP system to clean the equipment to remove the yeast remaining in the tank. Brewers need to spend time checking that all contact surfaces are cleaned and disinfected, including pipes, valves, and fittings. Because even a small amount of strain pollution will eventually affect the flavor of the beer. The contaminated yeast will also affect the taste of the final beer after continuous re-throwing.
Consistent Viability And Vitality In Pitches
How much live yeast is directly put into your wort is a key factor in judging the degree of fermentation. Taking the time to standardize this indicator will help prevent bad fermentation (incomplete fermentation). The common methylene blue staining protocol will be used to calculate the amount of slurry for the yeast before the ball is thrown. Also, the brewer can further confirm by directly technique the suspension cells in the beer after pitching.
It is important to measure the number of living cells in the yeast slurry, but more importantly, the health of these yeast cells. Vitality is an indicator of the health of yeast cells. The vitality test considers the capacity storage in the cell and the sound internal metabolic function. A healthy yeast cell should immediately start producing the necessary protein to process the wort, and replication will not have any problems. Methods to measure this characteristic are under development, but this method is very important to the success of yeast management.
Providing enough oxygen in the wort can enable yeast cells to grow and replicate efficiently. Although some of the oxygen is used for aerobic metabolism, most of it is taken into the cell vacuole and used to make unsaturated fatty acids necessary for cell reproduction.
The best way to ensure adequate oxygenation is to measure the dissolved oxygen of the wort. A common rule of thumb is:
1 ppm/degree Plato when using pure oxygen
8 ppm when utilizing air
Without discharging the wort into the atmosphere, online measurement is the most accurate way to get assurance. When the wort passes through the temperature, fluid flow, and gas flow change to enough level, a few clicks on these parameters. A standardized process will ensure that the DO concentration of each batch is consistent.
（5）Too Many Generations
Brewers need to understand the ability of yeast strains to continuously renew. With the batch release of yeast pulp, the yeast population will undergo genetic changes. The changes that occur will depend on many factors and will change according to different changes. The characteristics that may change include, but are not limited to flocculation capacity, flavor characteristics, viability/vitality, and decay rate. The composition and concentration of wort, storage method, hop varieties, fermentation temperature, and many other factors will have different effects on yeast strains.
The brewing business must keep fermentation records and use the fermentation records as a tool to understand the capabilities of yeast. By following the standard operating procedure (SOP) throughout the brewing process, a standard beer output can be observed. Use these records and observations to transfer how much beer you can produce from yeast.